Table. Antimicrobial susceptibility of the Shigella flexneri,serotype 2a pulsovar 21, isolated in Montreal, Quebec, Canada, 2015*.
| Antimicrobial agent | Disk diffusion, mm | MIC, mg/L | Interpretation |
|---|---|---|---|
| Ampicillin | 6 | ≥32 | R |
| TMP/SMX | 6 | ≥320 | R |
| Ciprofloxacin | 12 | ≥4 and 8 | R |
| Nalidixic acid | 6 | NA | R |
| Ceftriaxone | 33 | ≤0.25 | S |
| Cefixime | 26 | 0.25 | S |
| Azithromycin† | 6 | >256 | NS |
| Tetracycline | 6 | 32 | R |
| Chloramphenicol | NA | >256 | R |
| Amoxicillin-clavulanic acid | 14 | 16 | I |
| Ertapenem | NA | ≤0.5 | S |
| Gentamicin |
21 |
≤1 |
S |
| *I, intermediate; NA, not available; NS, nonsusceptible; R, resistant; S, susceptible; TMP/SMX, trimethoprim/sulfamethoxazole. †Azithromycin epidemiologic cutoff values for wild-type (MIC ≤8 mg/L) and non–wild-type (MIC ≥16 mg/L) Shigella flexneri (2) and the susceptibility and resistance breakpoints for the other 11 antimicrobial agents were CLSI Enterobacteriaceae breakpoints (2). | |||